1. Field
The present description relates generally to wireless communication and more specifically to precoding in a wireless communication system.
2. Background
Wireless communication systems are widely deployed to provide various types of communication such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple access terminals by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems. Typically, a wireless communication system comprises several base stations, wherein each base station communicates with the mobile station using a forward link and each mobile station (or access terminal) communicates with base station using a reverse link.
A problem in many communication systems is the receiver is located in a specific portion of an area served by the access point. In such cases, where a transmitter has multiple transmit antennas, the signals provided from each antenna need not be combined to provide maximum power at the receiver. In these cases, there may be problems with decoding of the signals received at the receiver. One way to deal with these problems is by utilizing precoding.
Precoding is a spatial processing technique that improves the signal-to-noise ratio (SNR) of a wireless link with multiple antennas. Typically, precoding may be used at the transmitter in a multiple antenna system. Precoding provides many advantages in improving signal-to-noise ratios which improves the decoding of the signals by the receiver.
Certain types of OFDMA systems are frequency division duplexed (FDD) OFDMA systems. In these FDD OFDMA systems, the transmission from the access point to the access terminal and from the access terminal to the access point occupy different distinct frequency bands. In FDD OFDMA systems feedback to perform precoding generally requires knowledge of the channel at the transmitter, e.g. access point, which is not available without substantial feedback. This feedback, generally in the form of the actual weights or vectors, requires a large amount of resources on control or signaling channels. This reduces data rates and increases the overhead required.
Thus, there exists a need in the art for a system and/or a methodology to enhance the performance of precoding.